Joint Collaborative Team on Video Coding (jct-vc) of itu-t sg16 wp3 and iso/iec jtc1/SC29/WG11
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- 7.3.2Lossless coding (0)
7.3Screen content coding (37)7.3.1Palette mode (20)JCTVC-Q0047 AHG10: Simplification of Palette Based Coding [W. Pu, R. Joshi, M. Karczewicz, F. Zou, J. Sole (Qualcomm)] Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
Initially reviewed in BoG on 3rd day (RC). This was a porting of P0303 AHG10 software from RExt 5.1 to RExt 6.0 basis. For further consideration in the context of potential future palette work. JCTVC-Q0169 AHG10: Adaptive Scan Order on Palette Based Coding [J. Zhu, J. Ye, K. Kazui (Fujitsu) Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future palette work.
7.3.3Other (17)JCTVC-Q0068 AhG8: On Sample Adaptive Band Value [G. Laroche, T. Poirier, C. Gisquet, P. Onno (Canon)] Initially reviewed in BoG on 3rd day (RC). For further consideration in the context of potential future SAO work. This contribution up an issue of how to compare filtering techniques (both for SAO and deblocking – somewhat previously discussed) where the filtering affects subsequent mode decisions in the prediction loop and it becomes hard to separate filtering effects from the perterbation of the mode decision process. JCTVC-Q0208 Crosscheck of JCTVC-Q0068 on AHG8: On Sample Adaptive Band Value [J. Xu, A. Tabatabai (Sony)] [late] JCTVC-Q0077 AHG8: Effectiveness of the HM Inter Search for Screen Content [K. Sharman, N. Saunders, J. Gamei (Sony)] Discussed 2nd day (Fri) (JRO). This contribution examines the reasons for the effectiveness of intra block-copy when using inter-predictive coding, noting that intra block-copy is effective for source material with a high degree of spatial repetitiveness, such as screen content. It is asserted that the current HM inter-prediction search is poorly suited for predicting such content and that substantial improvement may be made purely by changing the search algorithm. It is recommended that the inter search algorithm be considered before accepting any further new tools based solely on their inter performance, and that some test material be re-evaluated for its suitability for testing new tools. It is also pointed out that some of the screen content sequences (e.g. web browsing, ppt) seem to be very easy to compress. No specific proposal on alternative motion estimation. Adoption of Q0147 seems to be an appropriate start to solve the problem. JCTVC-Q0093 Single color intra mode for screen content coding [Y.-W. Chen, Y.-C. Sun, Y.-W. Huang, S. Lei (MediaTek)] Initially reviewed in BoG on 3rd day (RC). Was included in a SCC CfP response. For further consideration in the context of potential future SCC (possibly palette-related) work. JCTVC-Q0171 Cross-check of JCTVC-Q0093 [J. Xu (Microsoft)] [late] [miss] JCTVC-Q0112 In-loop color-space transform [L. Zhang, J. Chen, J. Sole, M. Karczewicz (Qualcomm)] Initially reviewed in BoG on 3rd day (RC). Includes report of gain for in-loop versus out-of-loop operation of the colour transform. For further consideration in the context of potential SCC work. JCTVC-Q0124 Improvements on 1D dictionary coding [J. Ye, S. Liu, S. Lei (MediaTek), X. Chen, L. Zhao, T. Lin (Tongji)] Initially reviewed in BoG on 3rd day (RC). Was not in the organization's formal CfP response. For further consideration in the context of potential SCC 1D dictionary work. JCTVC-Q0125 Crosscheck for JCTVC-Q0124 Improvements on 1D dictionary coding mode [R. Cohen (MERL)] [late] JCTVC-Q0149 1D Dictionary Coding [F. Zou (Qualcomm)] Initially reviewed in BoG on 3rd day (RC). The technique also part of a formal CfP response proposal (Q0031) when that proposal was operating in lossless mode. (Not cross-checked.) For further consideration in the context of potential SCC 1D dictionary work. JCTVC-Q0137 AHG 8: Adaptive Scaling of SAO offset [W.-S. Kim, J. Sole, M. Karczewicz (Qualcomm)] [late] Initially reviewed in BoG on 3rd day (RC). Further discussed in review of the BoG on 3rd day (GJS). Not screen content specific – more related to RExt as it is, and its design consistency. RExt, as it is, limits this technique to higher than 10 bit depth operation. Some participants questioned the value due to small reported gain and the need to continue to support the prior type of operation for version 1. No visual improvement was reported. Not a definite problem identified. No action.
Discussed 2nd day (Fri) (JRO). This contribution proposes a fast inter search method for screen content coding to better capture the spatial and temporal characteristics exhibited by screen content sequences like sharp edges, high spatial frequencies and non-monotonic error surface. It is asserted that the current HM’s inter prediction search is poorly suited for predicting such content and that substantial improvement may be made purely by changing the search algorithm. The following three modifications to inter search are proposed a) Multi stage approximated error cost computation with early exit at each stage b) Modified initial search method with a fixed diamond search traversing uniformly across the initial search space c) Modified early skip detection based on residual signals merge MV only. The proposed modifications are encoder only and do not affect decoder operation. For the lossy coding, the proposed inter search under SCC CfP test conditions show BD-rate gain of 8% and 9.2% for 1080p text and graphic sequences under random access and low delay configurations respectively. Results are on CFP test conditions and AHG8 test conditions. This indicates that different strategies of motion search may be necessary for screen content than for natural video. Since the gains of approx. 3% average over all sequences are significant, this should be carefully considered when assessing coding tools for screen content. Decision(SW): Adopt as non-default option to next version of RExt software. JCTVC-Q0241 Cross-check of JCTVC-Q0147 "On fast inter search method for screen content coding" [K. Sharman, N. Saunders, J. Gamei (Sony)] [late] JCTVC-Q0176 AHG8: String match in coding of screen content [W. Wang, Z. Ma, M. Xu, X. Wang, H. Yu (Huawei)] [late] Initially reviewed in BoG on 3rd day (RC). 2D string match of palette colour indices. (Not used in CfP response.)
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